The Flaviviridae family consists of 3 genera, the pestiviruses, the flaviviruses and the hepaciviruses. It also contains the hepatitis G virus (HGV/GBV-C), which has not yet been assigned to a genus. Pestiviruses such as the Classical Swine Fever Virus (CSFV), the Bovine Viral Diarrhea Virus (BVDV) and the Border Disease Virus (BDV) cause infections of domestic livestock (respectively pigs, cattle and sheep) and are responsible for significant economic losses world-wide. BVDV, the prototypic representative of the pestivirus genus, is ubiquitous and causes a range of clinical manifestations, including abortion, teratogenesis, respiratory problems, chronic wasting disease, immune system dysfunction, and predisposition to secondary viral and bacterial infections.
Vaccines are used in some countries with varying degrees of success to control pestivirus disease. In other countries, animal culling and slaughter are used to contain pestivirus disease outbreaks.
The World Health Organization estimates that world-wide 170 million people (3% of the world's population) are chronically infected with HCV. These chronic carriers are at risk of developing cirrhosis and/or liver cancer. In studies with a 10 to 20 year follow-up, cirrhosis developed in 20-30% of the patients, 1 to 5% of whom may develop liver cancer during the next ten years. The only treatment option available today is the use of interferon α-2 (or its pegylated from) either alone or combined with ribavirin. However, sustained response is only observed in about 40% of the patients and treatment is associated with serious adverse effects. There is thus an urgent need for potent and selective inhibitors of HCV.
The compound 3-[((2-dipropylamino)ethyl)thio]-5H-1,2,4-triazino[5,6-b]indole has been reported to selectively inhibit the replication of BVDV and other pestiviruses (Baginski S G et al., Proc. Natl. Acad. Sci. U.S.A. 2000 Jul. 5;97(14):7981-6). Currently, no pharmaceutical strategy is available for controlling pestivirus infections.
Coxsackie viruses belong to the enteroviruses of the Picornaviridae family. They cause a heterogeneous group of infections including herpangina, aseptic meningitis, a common-cold-like syndrome, a non-paralytic poliomyelitis-like syndrome, epidemic pleurodynia (an acute, febrile, infectious disease generally occurring in epidemics), hand-foot-mouth syndrome, pediatric and adult pancreatitis and serious myocarditis.
Currently only pleconaril (3-13,5-dimethyl-4-[[3-methyl-5-isoxazolyl)propyl]phenyl]-5-(trifluoromethyl-1,2,4-oxadiazole)) and enviroxime (2-amino-1-(isopropylsulfonyl)-6-benzimidazole phenyl ketone oxime) have been studied clinically for the treatment of infections with enteroviruses. Pleconaril is a so called “capsid function-inhibitor”; enviroxime prevents the formation of the RNA replicative intermediate. Enviroxime resulted in only modest clinical and virological benefit in some studies and no benefits in others. Clinical response with pleconaril has been observed in some studies, but the compound has not been approved by the Food and Drug Administration (hearing of Mar. 18, 2002).
Relevant disclosures include U.S. Pat. Nos. 4,914,108; 4,988,707; 4,990,518; 5,137,896; 5,208,242; 5,227,384; 5,302,601; 5,374,638; 5,405,964; 5,438,063; 5,486,525; 6,479,508; and U.S. Patent Publication No. US2003/0108862 A1, Canadian Patent No. 2423800 A1, German Patent Nos. 4211474 A1, 4236026, 4309969, 4318813, European Patent Nos. EP 0 138 552 A2, EP 0 706 795 A2, EP 1 132 381 A1, Great Britain Patent No. 2158440 A, PCT Patent Publication Nos. WO 00/20416, WO 00/39127, WO 00/40583, WO 03/007945 A1, WO 03/010140 A2, WO 03/010141 A2, WO 93/02080, WO 93/14072, WO 96/11192, WO 96/12703, WO 99/27929, PCT-US2004/43112, PCT-BE2003/000117, PCT-US2005/26606, Akamatsu, et al., “New Efficient Route for Solid-Phase Synthesis of Benzimidazole Derivatives”, 4:475-483, J. COMB CHEM., 2002, Cleve et al., “Derivate des Imidazo[4,5-b]-und Imidazo[4,5-c]pyridins”, 747:158-171, JUSTUS LIEBIGS ANNALEN DER CHEMACA, 1971, Kiyama, et al., “Synthesis and Evaluation of Novel Nonpeptide Angiotensin II Receptor Antagonists: Imidazo[4,5-c]pyridine Derivatives with an Aromatic Substituent”, 43(3):450-60, CHEM PHARM BULL, 1995, Mederski et al., “Synthesis and Structural Assignment of Some N-substituted Imidazopyridine Derivatives”. 48(48):10549-58, TETRAHEDRON, 1992, Yutilov et al., 23(1):56-9, KHIMIKO-FARMATSEVTICHESKII ZHURNAL, 1989. The disclosures of all citations set forth herein are expressly incorporated by reference to the extent such disclosures are relevant to the contents herein.
A need exists for compounds having therapeutic properties, such as greater oral bioavailability, reduced toxicity, optimal clearance, increased potency and the like against viruses belonging to the family of Flaviviridae including hepatitis C virus, and against viruses belonging to the family of Picornaviridae. These and other objects of this invention will be apparent to one skilled in the art from consideration of this specification as a whole.